"TV-Guide: Doesn't this retro format limit you to species we already know?
Berman: Absolutely not. In fact there are some species in Enterprise that will have the audience wondering, "Hey, how come we don't know these people by the time the 23rd- and 24th-century shows roll around?" And there are good reasons for that, as we will find out as Enterprise unfolds."

I read a similar response in another interview, which I naturally can't find now.